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Questions tagged [fat-metabolism]

The set of biochemical processes involved in the creation and utilization of lipids.

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If insulin secretion is ATP-induced, why don't fatty acids trigger insulin secretion?

I learned in my university physiology course that insulin is released by pancreatic beta-cells in response to glucose that is metabolized and thus increase cellular ATP levels, which in turn close ...
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Human Fat Adipose Tissue: Maximum Energy Transferred out per Day?

The article "A limit on the energy transfer rate from the human fat store in hypophagia" states that subjects with moderate activity levels are found to have a limit on maximum energy ...
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Does the body make alterations to fatty acids before their storage?

I was wondering if you would be at all able to help me with some questions I can’t find the answers to. I’m a first-year uni student doing some research for the fun of it but I’m really struggling to ...
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What is human body's overhead when storing calories into fat, and when retrieving calories from previously stored fat?

Questions: Suppose that someone ate an excess of 1000 kcal. How much of this 1000 kcal will become fat? Suppose that someone had a deficit of ...
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What is the connection between LDL, liver, and saturated fat?

I've been trying to learn about cholesterol, lipoproteins, and fats, but unfortunately, there is an ocean of confusing information on the internet. I don't have any solid background in biology, so ...
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Is Acetyl-CoA ever transported out of the cell, and in that case how?

Acetyl-CoA is sometimes formed as a result of protein katabolism. Certain cells (in the muscle for instance) can't use Acetyl-CoA to synthesize fatty acid. If there is no immediate need for energy, ...
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Does Chewing Food Properly Ensure that we gain Less Fat?

We recently went to a fast-food corner and I was told by my sibling that even if we chew a burger properly(slowly) converting it into a fine bolus, then it would not affect the amount of fat gained by ...
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Why does open olive oil keep so long?

This is a question about the biology of microorganisms, not about food safety. While most of our foods spoil quite quickly (it is recommended to throw food away after 2h in the danger zone), for some ...
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Do carboxylesterases, arylesterases and acylesterases count to the enzyme class of lipases? [duplicate]

I am currently examining the acyl transfer catalysis activity of several enzymes that I was told are all lipases. Through reading a couple of papers including these enzymes I found out that all of ...
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Does LSD "stay" in your fat storage and then "returns" back?

This rumor was told me by a very anti-drug person. A stance I agree with only lightly. The rumor was that when you take LSD, it stores itself in your fat storage, and then returns back in 3-6 months, ...
Timotej Leginus's user avatar
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Fatty acids into glucose

I have a question regarding the synthesis of glucose from fatty acids. In my book as well as in other posts on stackexchange, it states that fatty acids CANNOT be turned into glucose for the following ...
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Why are fatty acids synthesized in two carbon units?

Why does long-chain fatty acid synthesis involve the two-carbon precursor, malonyl CoA, rather than the one-carbon acetyl CoA (or even a three-carbon precursor). Is this because fatty acids with an ...
Sid's user avatar
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Can you eat more calories than the body can store?

I believe I have read that if the body takes in too many certain nutrients/vitamins, the body simply excretes them. How does this behave with calories? If I have a daily consumption of exactly 2,000 ...
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How much energy is used to construct a pound of fat tissue?

A widely cited figure is a pound of fat contains 3500 calories of energy in fatty acids. However, a pound of fat also contains adipose cells, arranged in adipose tissue, connective tissue etc. ...
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How much fat can the body absorb? Implications for daily fat distribution

This question is named analogous to this research: How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution http://ncbi.nlm.nih.gov/pmc/...
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Can fats clog veins or capillaries?

I know that so much fats running in the bloodstream could deposit in arteries, harden forming a plaque and cause atherosclerosis. But what about veins (which are formed from same types of layers as ...
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Why is glycerol the backbone of fat?

Fats are fatty acids joined onto the backbone of a glyercol (propane-1,2,3-triol). Why was glycerol seemingly chosen by nature to be the backbone of fats? Why can't it have been a butane -1,2,3,4- ...
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Why does the liver produce ketone bodies instead of exporting acetyl-CoA from beta-oxidation for use elsewhere?

Under conditions of low oxaloacetate in the liver, acetyl-CoA that cannot be oxidised in the TCA cycle is converted to ketone bodies, which can then be exported for use as fuel in non-gluconeogenetic ...
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How to calculate grams of fat used during hibernation?

In Humphries et al. 2002. Nature, the authors report number of grams of fat bats use during hibernation. However, their equations results in values in mlO2/g. How can one convert the energy ...
nya's user avatar
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What animal has fat with the highest energy density?

Fat is more energy-dense than protein and carbohydrates, it is not only an energy deposit but also an organ with many functions such as cushioning and metabolism regulations. I want to know are animal ...
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How does the inability to produce vitamin C helped weight gain?

I recently wondered how do dogs cope without vitamin C intake like us. A few Wikipedia pages later, I learned that our dry-nosed ancestors lost about two-thirds of the gene responsible for vitamin C ...
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How does the human body extract energy from ethanol?

I was talking about alcohol and obesity with a colleague. I always thought the only cause of that is the sugar that is found in most alcoholic beverages. But my colleague pointed out that ethanol ...
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Is returning cholesterol to the liver really performed by HDL?

Various answers in biology SE, including two quite upvoted ones (1, 2) claim that (in humans) returning cholesterol to the liver is done by HDL. If I understand correctly, Wikipedia's Reverse ...
Oren Milman's user avatar
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Could certain drugs enable one to consistently eat above TDEE or BMR without fat gains?

I heard anabolic steroids and stuff like DNP and ephedrine and etc. can somewhat enable one to eat more and get away with it without much or any fat gain, despite eating more than the body would ...
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Is it possible to stop more/extra fat from being stored in the body?

I don't mean simply by restricting eating or upping the activities, but a way to basically stop the body from adding more fat on itself down on the bio level. For example, I'm not too knowledgeable on ...
Goo Betch's user avatar
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Is there a relationship between HDL-C and LDL-C?

For a gentle introduction to cholesterol and its functions, see a great answer on SE Biology Whenever I read about how to deal with cholesterol level, the rule is to keep a low LDL fraction, ad a ...
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When consuming carbohydrates and fats together, why are the fats caloric?

If I understand things, and I most likely don't: mammals primarily use carbohydrates to produce metabolic energy when there are sufficient carbohydrates to do so. The use of fats for fuel requires ...
Michael Stachowsky's user avatar
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1 answer
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Where does weight go when you lose it? [duplicate]

When one loses weight, where does the lost poundage (I assume comprised mainly of fat) go? Is it urinated out? Defecated out? If a combination of both, does the percentage of each differ depending on ...
B. Clay Shannon-B. Crow Raven's user avatar
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How does body fat leave your body?

So I know that it’s not from tears or sweat because they are composed of mainly water and sodium, it’s not from going poo or pee as poo and pee are made of the parts of food that supply your body with ...
Nathan's user avatar
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Lipids that are not found in human body

I know that human body contains FA some of which are essential and the other is not depending on the ability of the body to synthesize them in a sufficient amount, but I need a reference of the lipids ...
Reem M.Al Haj's user avatar
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What is the source of the fat in adipose tissue?

I have heard the opinion that all of it comes from de novo lipogenesis of carbohydrates, but I'm skeptical. Is there evidence either way - either that dietary fat definitely gets stored in the adipose ...
Abu Dhabi's user avatar
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Why do humans lose subcutaneous fat from the extremities with age?

Why does fat tissue die and shrink on the hands, knees, and lower legs of most people as they age, even when they are overweight? In most people, their bone definition becomes much more visible around ...
user45506's user avatar
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2 answers
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Why do humans lose subcutaneous fat tissue with age?

Why exactly do humans lose subcutaneous fat tissue with age? It appears that we either lose fat cell volume or we might actually be losing the number of fat cells with age. One hypothesis is that as ...
user45506's user avatar
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How would a medication cause a one to maintain a different weight?

This isn’t really a medical question, I’m just really curious about this. I was maintaining weight A and then started taking a medication that brought me to weight B. While on the medication, I ...
Melanie Shebel's user avatar
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When you lose weight, how does the mass exit your body?

As a thought experiment, consider the case of Angus Barbiery, who allegedly lost almost 200kg in about a year by not eating at all, save for necessary nutrients provided as supplements. My question ...
Tomáš Zato's user avatar
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What happens to lipoprotein lipase after a sugar only diet?

Insulin increases the activity of lipoprotein lipase thay allows cells to take in lipids from chylomicrons in the blood. If a person takes a sugar only meal like drinking coke, insulin is released. ...
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Why are fatty acids consisting of even number of carbons predominant?

Most of the fatty acids in animal biology consist of even number of carbons in its parent chain. What property of such fatty acids cause the biological systems to prefer them over the odd counterparts?...
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1 answer
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Extra-mitochondrial conversion of Acyl Carnitine to Acyl CoA

Normally fatty acids in the form of acyl CoA are converted to acyl carnitine in a reaction catalysed by carnitine palmitoyltransferase I (CPT1), which is also known as carnitine acyltransferase I. ...
Aaron43's user avatar
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Why does the amount of adipose tissue contribute the most to the total body water amount in humans?

I don't quite get this concept. An obese individual will have a greater fat content in their body, and thus will have 45% water in their bodies (for example), versus a slim person that will have 75% ...
ScienceGirl1234's user avatar
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Is dietary fat directly stored in adipose tissue or is it immediately metabolized?

I know that fat goes to adipose tissue and even sugar gets converted to fat and goes to adipose tissue, but what happens to fat (unsalted cow milk butter) I just ate? Will it give me energy now, or ...
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How are micelles formed from the byproducts of emulsification in fat digestion?

It is known that fat droplets are made into emulsion droplets via the addition of bile salts. It is then said that the emulsion droplets are made into micelles through some sort of lipase, which can ...
A. Radek Martinez's user avatar
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3 answers
7k views

Breathing faster to lose (more) weight?

I understand that when the human body loses weight, the vast majority of that weight is lost as $CO_2$ (and a small bit is lost as water). I expect the predominant way $CO_2$ exits the body is through ...
electronpusher's user avatar
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After fat is burned from one part of the body, is fat moved around the body?

If you go running, for example, and burn fat from your legs, does your body send fat from other parts of the body to that area? If so, why would it do this?
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How can grass-fed livestock generate fat?

How can herbivorous cattle get fat? These animals eat only grassy substances, think of cattle, buffalo, goats etc. For example, wheat grass contains 0% fat, and its nutritional value is limited to ...
murmansk's user avatar
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4 votes
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Is the amount of cholesterol the body produces affected by how much cholesterol you take in with food?

In the past I've been told multiple times that if you don't eat foods containing cholesterol, your body will increase its production of cholesterol to balance out the lack of nutritional cholesterol. ...
zepp133's user avatar
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How does the body determine where to deposit fat reserves?

People's bodies store fat in similar areas, but often there are subtle differences in which areas are first or slightly more effected. This seems to also be apparent with morbidity, where certain ...
Eliot G York's user avatar
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1 answer
4k views

Is palmitic acid really that dangerous?

According to Wikipedia, "Palmitic acid is the most common saturated fatty acid found in animals, plants and microorganisms. It is also the first fatty acid produced during fatty acid synthesis and is ...
ManRow's user avatar
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1 answer
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Why is glycerol kinase absent from adipocytes but present in the liver?

Why don't adipocytes have the enzyme, glycerol kinase? Wouldn’t it be more efficient for them to utilise glycerol present to synthesize triglycerides than to get it from the liver? So what is the ...
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Is there such substances that body can only send to storage (as fat)?

I watched video with statement that there are such part of substance in potato chips which body can't use ("empty calories"), that they surely will be stored as fat. It was here on 12:23: https://...
R S's user avatar
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Rate of production of enzymes in human [closed]

In the metabolic pathways, each of the reaction needs an enzyme(protein) in order to occur successfully. Is there any quantitative measure that can be associated to this enzyme? Like synthesis rate of ...
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